Prolonged Shutdown Research Articles

Abstract 4117646: The Ultimate Test in Hemocompatibility: HeartMate3 Restart After Prolonged Pump Shut Down

Introduction: The HeartMate 3 (HM3) LVAD, was shown to have a higher survival free of hemocompatibility related adverse events (HRAE) compared to its predecessors (HM2, HVAD). Superior HM3 outcomes are attributed to wide blood flow pathways coupled with frictionless movement and intrinsic pulsatility, reducing shear stress and blood stasis. It is unknown if improved hemocompatibility can withstand pump restart after prolonged shutdown. We herein report a case of HM3 pump stoppage without subsequent HRAE. Case Presentation: A 41-year-old male underwent HVAD implant in 2019 for advanced non-ischemic cardiomyopathy. This was exchanged to HM3 for recurrent neurological events despite therapeutic anticoagulation. Ten months after exchange, he awakened one morning to find his LVAD had been off for an unknown period but had not heard any device alarms (85dB if on battery power, 165dB if on wall power). Since he felt well he changed to battery power resulting in immediate pump restart. Log file analysis showed pump stoppage 2 am – 10 am, without preceding low flow alarms or power elevations. Management and Outcomes: In the ER INR was 1.5 (2.8 one week prior) and systemic heparin was started. Evaluation included: 1) CT brain without acute infarcts 2) echocardiogram without intracardiac thrombus 3) CT Angiography with patency of the inflow cannula and outflow graft 4) stable serial LDH measurements. The controller was exchanged, and analysis noted normal function. 1-year later the patient is maintained on warfarin and aspirin 325mg without further HRAE. Given the patient’s neurologic history and pump stoppage event, we did not invoke ARIES trial guidance and thus continued aspirin. Conclusion: Pump stoppage occurs when there is complete battery depletion, disconnection of both power leads, or the percutaneous lead from system controller. Our case is unique in that the duration of pump shutdown was 8 hours and INR subtherapeutic, without HRAE in the background of neurologic events on HVAD support. It has been previously reported that complete outflow graft thrombosis can occur shortly after LVAD decommissioning. The HM3 User Manual recommends restarting the pump immediately if off for a few minutes and using clinical judgment for longer durations due to increased risk for thromboembolic events. Our case adds to the paucity of existing data on improved hemocompatibility of the HM3 during rare circumstances of the ultimate test in hemocompatibility: complete pump shut down.

Determine the Profiles of Power Consumption in Commercial Buildings in a Very Hot Humid Climate Using a Temporary Series

With the growth of the nations, the commercial and public services sectors have recently seen an increase in their electricity usage. This demonstrates how crucial it is to understand a building’s behavior in order to lower its usage. This requires on-site data collection by qualified professionals and specialized equipment, which represents high costs. However, multiple studies have demonstrated that it is possible to find electricity-saving strategies from the study of electricity usage, recorded in an hourly period or less, captured by smart meters. In this context, the present study applies a methodology to determine useful information on the operation and characteristics of public buildings on the Ecuadorian coast based on the data gathered over a period of five consecutive months from smart meters. The methodology consists of four steps: (1) data cleaning and filling, (2) time-series decomposition, (3) the generation of consumption profile and (4) the identification of the temperature influence. According to the results, the pre-cooling of spaces accounts for 5% of all electricity used in the commercial buildings, while prolonged shutdown uses 10%. Approximately USD 1100 per month would be spent on the main building and USD 78 on the agency as a result.

Towards unsupervised fault detection for offshore wind turbine cable protection systems using contrastive learning

As offshore wind power expands globally, it is essential to ensure the reliable operation of components of such critical infrastructures. A less explored instance of such components, which are though essential in terms of operation, is found in subsea turbine cables and their protection systems, whose failure can incur prolonged shutdown periods and costly repairs. We propose a novel unsupervised machine learning approach exploiting use of Distributed Acoustic Sensing (DAS) data and contrastive learning for monitoring offshore wind turbine Cable Protection Systems (CPSs). A Transformer neural network adapted for time-series ingests the high-frequency, noisy DAS CPS time-series measurements, and is trained to learn a coherent representation of the data using a contrastive learning scheme that enforces temporal and positional consistency in the latent space. This latent representation can then be used to perform anomaly detection in an unsupervised manner, alleviating the need for costly labeled offshore anomaly data. We demonstrate that a coherent representation of the data is learnt by the model, which we then use to detect synthetic anomalies and an actual CPS stabilization event.

Hydrogen Storage and Combustion for Blackout Protection of Mine Water Pumping Stations

Global warming increases the risk of power outages. Mine water pumping stations pump approximately 100 million m3 of water per year (2023). The cessation of mine water pumping would expose neighboring mines and lower lying areas to flooding. The pumping stations have some containment, but a prolonged shutdown could cause environmental problems. Remediation of the resulting damage would be costly and time-consuming. The combination of the problems of dewatering abandoned mines and storing energy in the form of hydrogen to ensure continuity of power supply to pumping stations has not been the subject of extensive scientific research. The purpose of this paper was to develop options for protecting mine water pumping stations against the “blackout” phenomenon and to assess their investment relevance. Six technically feasible options for the modernization of mine water pumping stations were designed and analyzed in the study. All pumping station modernization options include storage of the generated energy in the form of green hydrogen. For Q1 2024 conditions, the option with the partial retail sale of the produced hydrogen and the increased volume of produced water for treatment is recommended for implementation.

Abstract 1954: Development of highly potent, covalent, and selective inhibitors to target PI3Kα in cancer

Abstract Aberrant PI3K signaling is linked to various forms of cancer and proliferative disease. Approved clinical therapies targeting overactive PI3K are scarce and often accompanied by severe adverse effects due to lack of PI3K isoform selectivity. We recently reported a proprietary covalent proximity scanning (CoPS) approach to selectively target distant cysteines outside of the ATP-binding pocket in kinases. Using CoPS, we developed isoform specific, irreversible covalent PI3Kα inhibitors (cPI3Kαi) with outstanding target engagement profiles. Here, we report structure-guided scaffold and linker-optimizations resulting in cPI3Kαi with long-term and rapid inhibition of PI3Kα. Cellular activity was improved exploiting additional protein-inhibitor interactions inspired by X-ray crystallographic data, and introduction of structural elements to increase cell permeability. The cPI3Kαi series showed enhanced cellular potency and excellent on-target engagement. Kinetic parameters and covalent bond formation were determined using TR-FRET, nanoBRET tracer displacement assays, and LCMS/MS based proteomics. With our new cPI3Kαi, IC50s of PKB/Akt phosphorylation, pPKB/Akt recovery after drug washout, and growth inhibition experiments were performed in cancer cell lines harboring activating PIK3CA or inactivating PTEN mutations. Efficient and long-lasting inhibition of PKB/Akt phosphorylation was observed in PIK3CA mutant cell lines, while loss of PTEN was associated with partial responses, consistent with contributions of other class I PI3K isoforms to signal reactivation. A dynamic FOXO cytosolic/nuclear translocation assay was used to monitor distal PI3K signaling: cPI3Kαi blunted PI3K signaling rapidly with rates identical to the reversible BYL719/alpelisib. After drug washout, inhibition by BYL719/alpelisib was relieved within minutes, while a complete and prolonged shutdown of downstream signaling events was observed in PIK3CA mutant cell lines but not in cell lines where PTEN function was lost. This relapse in downstream signaling explains the lack of efficacy of PI3Kα selective inhibitors in models with PTEN loss and demonstrates that persistent inhibition across the PI3K pathway is required for efficacy. In summary, the new cPI3Kαi display outstanding specificity and cellular activity in PIK3CA-mutated cancer cells, and support the further development of cPI3Kαi as future clinical candidates and an alternative to established reversible inhibitors. Citation Format: Luka Raguž, Theodora A. Constantin, Lukas Bissegger, Erhan Keleş, Clara Orbegozo, Thorsten Schäfer, Rohitha Sriramaratnam, Chiara Borsari, Matthias P. Wymann. Development of highly potent, covalent, and selective inhibitors to target PI3Kα in cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1954.

Hydrogenerator early fault detection: Sparse Dictionary Learning jointly with the Variational Autoencoder

Monitoring the continuous health status of a Hydraulic Turbine Generator Unit (HTGU) is a strategic task to prevent any unexpected downtime. In addition to the loss of energy production following a prolonged shutdown, the various maintenance costs represent an undesirable effect due to unanticipated failure. One of the main functions of a condition-based maintenance (CBM), is the early detection of any unexpected changes in a machine behavior. Indeed, being able to detect any drift or change in behavior compared to a reference behavior represents a major challenge in the monitoring of complex machines like a HTGU. In this paper, an early anomaly detection model for HTGU using Variational Autoencoders (VAEs) and Sparse Dictionary Learning (SDL) is proposed. The combined reconstruction error thus obtained from the VAE-SDL model is used as an early fault detection. Experimental tests on vibratory signals show that the two models thus joined increase the sensitivity as well as the robustness of the anomaly detection.

Effect of tramp oil ingress in cold rolling oil bath leading to white spot defect on CRCA at Tinplate mill

Cationic rolling oils for cold rolled steel manufacturing is based on dispersion technology. Cationic surfactants present in rolling oil allows the oil to remain dispersed in water phase thus aiding lubrication. During operational conditions, tramp oil ingress in the form of lube oil, hydraulic oil and grease often happens and it remain dispersed in roll coolant bath in smaller quantity without creating any surface blemishes on cold rolled steel. During an unprecedented mechanical shutdown in Tin plate cold rolling mill, after mill startup random white spot defect with greyish centre suddenly started appearing on cold rolled sheet leading to quality deviations and mass rejections. Prolonged shutdown disturbed the overall equilibrium condition of the tramp oil dispersion within the rolling oil emulsion. This study highlights the role of tramp oil separation within the rolling oil bath leading to the defect initiation. The deposition of alkaline cleaner during the ECL process further retards the burn off properties of the tramp oil resulting in the defect formation. Techniques like microscopy, SEM-EDS and Raman spectroscopy were employed to understand the nature and morphology of the defect formation whereas TGA and XRF were employed to investigate and identify the probable source.

Results of validation and cross-verification of the ROK/B design code on the problem of loss of cooling in the spent fuel pool *

The procedures of validation and cross-verification of the newly developed computational code ROK/B are described. The main problem solved using the ROK/B code is the substantiation by calculation of the coolant density in the spent fuel pool (SFP) and the temperature regime of the fuel assemblies during a protracted shutdown of the cooling systems (break in the supply of cooling water). In addition to the above, it is possible to use the ROK/B code to carry out calculation of an accident with the discharge of the coolant from the SFP with simultaneous prolonged shutdown of the cooling systems. The ROK/B code allows carrying out calculations for various types of designs of the fuel assemblies and VVER reactors, in particular, VVER-1000, VVER-1200 and VVER-440 power units with single- and two-tiered fuel assembly arrangement, with clad pipes in racks (for compacted assemblies storage) and pipes without cladding, with cased assemblies and caseless ones. During fuel reloading, a high level of the coolant is maintained, which makes it possible to do “wet” transportation of the assemblies from the reactor to the SFP. The mathematical model for heat and mass transfer calculation, including the boiling coolant model, implemented in the ROK/B code, includes: the motion equation, equations for calculating the enthalpy along the height of the fuel section of a fuel assembly with natural circulation of coolant within the channel containing the fuel assembly (lifting section) and in the inter-channel space (lowering section), the equation of mass balance between the channels of the racks with assemblies and in the inter-assembly space and the amount of evaporated (and outflowed) water, the heat balance equation for a fuel rod in a steam environment. The system of equations is supplemented by closing relations for calculating the thermal physics properties of water and steam, fuel and cladding materials, as well as the coefficients of heat transfer from the wall to the steam, hydraulic resistance and density of the steam-water mixture in the channels, and the heat released in the reaction of steam with zirconium. Validation of the computational code was carried out on the basis of the data of the ALADIN experiment performed by German specialists and the data of JSC OKB Gidropress. Cross-verification of the ROK/B code was carried out in comparison with the results of calculation using the KORSAR/GP and SOKRAT/B1 codes. Based on the results of the validation, it has been concluded that the deviation of the ROK/B results from the experimental data is not more than 2 to 10% (10% for the option with a fuel rod power of 20 W). Based on the results of cross-verification, it has been concluded that the discrepancy between the ROK/B results and the calculation results for the KORSAR/GP and SOKRAT/B1 codes is not more than 0.5% (for SOKRAT/V1) and less than 10% (for KORSAR/GP).

Status of psychological health of students following the extended university closure in Bangladesh: Results from a web-based cross-sectional study.

Students' severe affective mental distress has emerged as significant public health attention globally because of the disastrous effects of coronavirus disease 2019 (COVID-19). The current study aimed at exploring the prevalence of two alarming psychological distresses, depression and anxiety, among university students following a prolonged shutdown of educational institutions in Bangladesh. A cross-sectional online-based study was conducted by deploying two standard scales to assess the depression and anxiety among Bangladeshi students from various universities amid the 2nd stream of the COVID-19 pandemic. A total of 568 Bangladeshi university students participated in this questionnaire-based survey through various social media platforms. Frequency and percentage distribution as univariate, chi-square (χ2) test as bivariate, and logistic regression as multivariate analyses were applied to investigate the prevalence of depression and anxiety and their associated various sociodemographic factors. After cleaning and eliminating the partial data, we analyzed 465 responses, where 42% were female and 64.3% were from public universities. Both mental disorders were prevalent in more than 50% of Bangladeshi university students. The students from the private universities were two times and 2.7 times more depressed and anxious, respectively than the students from the public universities. In addition, the students who became incomeless had significantly more anxiety (adjusted odds ratio [AOR] = 1.711; p = 0.018) than those who did not lose income source during the COVID-19 lockdown. The present study revealed that more than 50% of Bangladeshi university students were suffering from depression and anxiety. Several effective measures must be assured by the concerted efforts of university authorities, educationalists, and the Government to alleviate these distressing mental health burdens.

Technological features of metal structures strengthening by gluing of high-strength FRP-systems during reconstruction

The building heritage of Ukraine includes numerous examples of metal structures, especially used in industrial buildings and for large-span structures. The use of metal structures in construction is primarily due to their mechanical properties. They are frost-resistant and can withstand temperatures down to -65 degrees, tough, resistant, durable and reliable. They can also be used in areas with increased seismic activity. But, in certain situations metal structures need to restore or strengthen due to structural defects, wear of load-bearing elements, as well as in order to increase the bearing capacity. In some cases, strengthening with fiber-reinforced polymer composites (FRP) gives better results than traditional methods with metal strengthening.
 A significant part of the Ukrainian architectural and historical heritage is made up of buildings and structures using metal structures. The first designs were made of cast iron or wrought iron (machined or tinned), but they subsequently developed rapidly along with the evolution of methods for forging mineral iron.
 The main cultural reason for the restoration of old metal structures that guarantee structural functionality and load-bearing capacity, based not only on the need to preserve their historical origin, but also on the value of the landscape in which they are located.
 Long-term operation of buildings and their structural elements made of metal without timely maintenance and major repairs, insufficient strength of structural materials, as well as changes in weather conditions and current regulatory documents in Ukraine, often leads to the need to recalculate the load-bearing metal structures of the building frame and strengthen them with the most effective methods, both from the point of view of reliability and from the point of view of profitability, which is influenced by prolonged shutdown of enterprises, stoppage of the production process or the inability to use the adjacent territory to carry out reconstruction work.
 The article discusses the technological features of metal structures strengthening by gluing high-strength FRP-systems during the reconstruction of building, and also provides basic recommendations for the installation, monitoring and maintenance of strengthened elements.

Investment appraisal: Akwaaba university hostel project

Learning outcomes After completing this case, students should be able to: identify and compute relevant cash flows in relation to a real estate project and compute the net present value (NPV). Determine the target return or cost of capital (by looking at historical economic indicators). Design or formulate a sensitivity analysis to determine the drivers of the project value. Evaluate real estate and other investments taking qualitative and quantitative factors into consideration. Demonstrate the computation of a break-even rate to determine the minimum or maximum revenue or cost required for a project to be viable. Case overview/synopsis This case study is about the Golden Beak Securities Pension Fund that wanted to invest in a Hostel Project in one of the universities in Ghana. Most universities in Ghana faced an acute shortage of on-campus accommodation. Also, the Government of Ghana, in 2017, implemented a programme to make Senior High School in Ghana free. This was expected to increase the number of students who will enter the existing universities. The project was therefore seen as strategic, as it would help ease the pressure of on-campus accommodation while providing diversification for the pension fund. As part of the investment committee’s (IC) quest to improve the skill set available to it, especially in relation to real estate investments, Esi Abebrese was appointed as one of the members of the IC of GSB. Her main task was to collect information on key macroeconomic variables, as well as granular information on project costs and revenues and conduct investment appraisal. Esi was scheduled to make a presentation to the IC on the 15th of October 2019 following which the Committee will debate and make a decision. The project had an estimated cost of GH¢52m with a total number of 3,424 student beds and ancillary facilities. Undertaking the project required moving funds from investments in money market securities with one of the banks in Ghana. The investments in the money market securities were currently yielding about 16% a year. The determination of the cost of capital was critical and Esi and Nana eventually settled on a long-term weighted average cost of capital of 14%. This was after considering the trend of inflation, monetary policy rates, treasury rates, stock market returns and a report on returns on commercial real estate properties in Ghana. An exit capitalisation rate of 20% was also estimated for the purposes of determining the value of the property at the end of the investment horizon. Esi also obtained estimates of cost and revenue for the project and proceeded to carry out a feasibility analysis on the project. This consisted of an NPV analysis and sensitivity analysis on various factors to determine the drivers of the project value. The IC had to take several factors (both quantitative and qualitative) into consideration before making a decision. Esi believed that these factors included the diversification of the fund’s assets, the return on investment, potential oversupply of hostel accommodation, the social responsibility of providing student accommodation and the impact of any prolonged shutdown of the university. Complexity academic level Masters/advanced undergraduate. Supplementary materials Teaching Notes are available for educators only. Please contact your library to gain login details or email support@emeraldinsight.com to request teaching notes. Subject code CSS 1: Accounting and Finance.

Impact of COVID-19 on Pancreatic Cancer Research and the Path Forward

The severe acute respiratory syndrome coronavirus-2 and related coronavirus disease 2019 (COVID-19) pandemic have deleteriously affected cancer research worldwide, including basic, translational, and clinical fields, because of prolonged shut-down of research laboratories consequent to lockdown restrictions, curtailment of researchers’ laboratory access, decreased availability of patient samples, and clinical trial disruptions.1–5 In addition, cuts in funding are significantly contributing to the impact and are threatening the viability of cancer research as a whole.

Changing Trends in Advertising, Anti-Covid Products and Brand Promotion

The tools, techniques as well as the platform have shifted for the advertisement during the Covid 19 pandemic. Sudden rise in the net worth of OTT platforms, Pharmaceutical, Insurance and Health care Companies reflects the change in market dynamics. Home delivery of various items, work from home and lockdowns lead to the emergence of some new sectors in the market. Spending of hygiene, immunity booster and home luxury products has not remain the choice of Urban population only, rather it has became a crucial need of the whole country. Online Gaming, social media platforms, and digital marketing is experiencing a surge in it’s demand and expecting competitors in the market (Oesterkloeft, 2020). Marketers would need to build much more fast reaction industry trends within and with agency, so that innovative messaging change quickly. As the situation deepens, distant manufacturing and creativity resources are becoming more and more vital. For instance, Nike swiftly took on a new slogan: "Play inside, play outside." (Konig et al., 2020).As India is witnessing the 2ndphase of the covid lockdown, the govt and the public need to figure out which of these improvements will last and affect media consumption trends in the long run. The prolonged shutdown is being expected to put declining pressure on consumer buying power, resulting in continued low spending on discretionary and planned purchases. The most gain will come from e- content exposure and e-commerce, which will see a staticgrowing change in the baseline. Consumers would place a higher value on brands that demonstrate credibility, genuine experience, unprejudiced patriotism, and social responsibility.

Impact of Strong Global Brands of Cultural Institutions on the Effective Development of Regions in the Context of the Covid-19 Pandemic

Research background: In the context of the coronavirus pandemic, when cultural objects were unable to function normally for a long time, their income has significantly decreased, and state support is not enough to implement strategic projects. This is due to a sharp decline in the incomes of the population of these countries and a prolonged shutdown of large- scale production, even the stagnation of entire sectors of the economy. Purpose of the article: The article is devoted to the problem of the formation of strong brands of cultural institutions, in particular, art museums and galleries and their impact on the competitiveness of the region. Methods: We use statistical, and regression methods for analysis, which are used to assess the mutual influence of traffic flows to museums and other cultural objects on the total income in the art market. Findings & Value added: The analysis showed that work on the image, strengthening the brands of cultural institutions, increasing the level of recognition in the world and close ties with recognized art-dominants in the future will allow cultural institutions to attract significant financial flows and improve their competitive position in the world market. As the scientific increment can be considered, the results of analysis the relationship between the strong brands of art museums and other cultural objects and the tourist attractiveness of their locations, as well as the mutual influence of cultural object brands on the territory’s brand. It is proposed to modify the methodology for evaluating the brand value in an art Museum or gallery.

Developing SupercomputerTwins Of NuclearPowerPlants ForVarious Applications With The Use Of Russian 3D Numerical Analysis Codes

The article describes the technology of the supercomputer twin of a nuclear power plants, which describes the main circulation circuit of the coolant. The technology is based on a joint one-dimensional and three-dimensional description of a reactor expanding the field of application of traditional one-dimensional system codes for describing fundamentally three-dimensional processes in reactor plenum. A description of the technology and verification data based on experimental studies is provided. The application of this technology to the analysis of the partial operating modes of the RITM-200 reactor plant was demonstrated, which made it possible to mitigate power limitations when disconnecting part of the heat exchange surface of the steam generator, reduce the costs of repair of the reactor plant associated with the replacement of steam generator cassettes, and avoid prolonged shutdown of a nuclear icebreaker.

Field testing of a household-scale onsite blackwater treatment system in South Africa

Innovations that enable cost-effective and resource-conserving treatment of human waste are required for the 4.2 billion people in the world who currently lack safe and reliable sanitation services. Onsite treatment and reuse of blackwater is one strategy towards this end, greatly reducing the need to transport wastewater over long distances either via sewers or trucks. Here, we report on the field testing of a prototype onsite blackwater treatment system conducted over a period of 8 months. The system was connected to a women's toilet in a public communal ablution block located in an informal settlement near Durban, South Africa. Liquid waste was treated by separation and diversion of large solids, settling of suspended solids, and filtration through activated carbon prior to disinfection by electrochemical oxidation. System performance was monitored daily by measurement of chemical and physical water quality parameters onsite and confirmed by periodic detailed analysis of chemical and biological parameters at an offsite lab. Daily monitoring of system performance indicated that the effluent had minimal color and turbidity (maximum 90 Pt/Co units and 6.48 NTU, respectively), and consistent evolution of chlorine as blackwater passed through the system. Weekly offsite analysis confirmed that the system consistently inactivated pathogens (E. coli and coliforms) and reduced chemical oxygen demand and total suspended solids to meet ISO 30500 category B standards. Significant reductions in total nitrogen load were also observed, though these reductions often fell short of the 70% reduction required by ISO 30500. No significant reduction in total phosphorus was observed. Maintenance requirements were identified, and the resilience of the system to restart following a prolonged shutdown was demonstrated, but significant improvements are required in the design of the solid/liquid separation mechanism for application of this system in a wiping culture.

PCC pilot plant studies with aqueous potassium glycinate

The present research work discusses the suitability of aqueous potassium glycinate (KGly) in a PCC-pilot plant. Reference is made to measurement results with aqueous sodium glycinate (NaGly). The use of real power plant flue gas and the well-conceived dimensions of the test facility enable industry-related conditions for full-scale applications.Although 40wt% KGly has faster kinetics in unloaded state, no enhancements in plant operation could be achieved in comparison to 40wt% NaGly. Just like with NaGly, the difficult feasibility of KGly regeneration leads to slow CO2 absorption rates, resulting in a huge energy demand >5.5 GJ/tCO2. A far lower energy demand of 3.68 GJ/tCO2 was measured for 30wt% MEA. The required solvent flow rate for reaching the optimal operating point is high (L/G-ratio=9l/m3). The pilot plant was operated with a massive reduced flue gas flow (40% of the dimensioning) in order to prevent instable operation and to reach the desired CO2 separation efficiency of 90%. During a prolonged shutdown, excessive carbonate was formed in the desorber column, resulting in a further reduction of the flue gas flow rate. Measurements of the ammonia content of the treated flue gas exhibit that the solvent degrades enormously.

Studies on the separation of 99mTc from large excess of molybdenum.

Due to aging and unexpected prolonged shutdown of nuclear reactors producing ⁹⁹Mo for ⁹⁹Mo/ 99mTc generators it was necessary to explore the alternative methods of technetium-99m production. The first choice were the accelerators. Three years ago IAEA (International Atomic Energy Agency) initiated the Coordinated Research Project "Accelerator-based Alternatives to Non-HEU production of Mo-99 /Tc-99m" aimed at direct production of 99mTc in proton accelerators using the ¹⁰⁰Mo(p,2n)99mTc reaction. POLATOM is participating in this enterprise together with the Heavy Ion Laboratory of Warsaw University and the Institute of Nuclear Chemistry and Technology. ⁹⁹Mo/99mTc solutions and pure 99mTc used for generators production or milked from ready to use generators were used in experiments. Commercial chromatographic and laboratory-prepared columns were used for separation. The peristaltic pumps were used for solutions delivery onto the columns. Radioactivity of eluted ⁹⁹Mo and 99mTc was measured using high resolution gamma spectrometry or ionisation chamber in case of high radioactivity. For separation, three different chromatographic methods were used, one based on ion exchange and two on extraction. Synthetic mixtures simulating the real solutions were used. 99mTc is quantitatively bound in the Dowex-1 × 8 column whereas molybdenum is only slightly retained and totally rinsed with 2M NaOH. 99mTc is eluted with TBAB. The elution yield has been reproducible and amounted to 78%. The AnaLig Tc-02 resin column was used for 99mTc retention. Residual Mo was removed by rinsing with 2M NaOH and 99mTc eluted using small volume of water. The recovery was equal to about 85%. Using C-18 column coated with PEG over 80% of 99mTc was recovered in about 50 mL of water. The reduction of volume was necessary. The recovery of 99mTc was the highest using AnaLig Tc-02 resin. Time of 99mTc separation is the shortest for AnaLig Tc-02 resin and it is not higher than 100 minutes and it can further be shortened.

Comparing shut-down strategies for proton exchange membrane fuel cells

Application of system strategies for mitigating carbon corrosion of the catalyst support in proton exchange fuel cells (PEMFCs) is a requirement for PEMFC systems, especially in the case of systems for transport application undergoing thousands of start-ups and shut-downs (SU/SD) during its lifetime. This study compares several of the most common shut-down strategies for 1100 cycles SU/SD cycles at 70 °C and 80% RH using commercially available fuel cell components. Each cycle simulates a prolonged shut-down, i.e. finishing each cycle with air filled anode and cathode. Furthermore, all start-ups are unprotected, i.e. introducing the H2 rich gas into an air filled anode. Finally, each cycle also includes normal fuel cell operation at 0.5 A cm−2 using synthetic reformate/air. H2 purge of the cathode and O2 consumption using a load were found to be the most effective strategies. The degradation rate using the H2 purge strategy was 23 μV cycle−1 at 0.86 A cm−2 using H2 and air at the anode and cathode, respectively. This degradation rate may be regarded as a generally low value, especially considering that this value also includes the degradation rate caused by unprotected start-ups.

Highlights of the “Space Weather Risks and Society” Workshop

Highlights of the “Space Weather Risks and Society” Workshop